
Agere Systems Inc.
221
Data Sheet
July 2001
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
16 Parallel Peripheral Interface (PPI)
(continued)
16.3.4 PPI Pull-Up Enable Register
The
PPI port pull-up enable register
is used to enable a pull-up resistor on the corresponding PPI I/O. If a bit in
the register is 1, the corresponding pin is connected to an internal pull-up. Table 194 below shows the format of the
PPI port pull-up enable register
. On reset, all bits of this register are set to 1.
For the case of multiplexed chip pins, the
PPI pull-up enable register
controls the connection of pull-up resistors
to the I/O pins even if the pins are being used for non-PPI functions.
When held in reset, the PPI pull-up bits in the PPI Port Pull-up Enable Register (Table 194) are configured to be
inactive
on all inputs. Immediately after reset, the pull-ups are
active
on all inputs.
Table 194. PPI Pull-Up Enable Register
16.3.5 PPI Port Data Clear Register
The
PPI port data clear register
is a 32-bit register containing 16 used bits, one for each of the general purpose
PPI
I/O pin. Each of the bits corresponds to a bit in the
PPI port data register
.
The
PPI port data clear register
is not a real hardware register, but is instead an address used to clear bits in the
PPI port data register
. When a write is performed to the
PPI port data clear register
, each bit that is set to 1
results in the corresponding bit in the
PPI port data register
being cleared to 0. The other bits of the
PPI port data
register
remain unchanged.
A read of the
PPI port data clear register
address returns the data in the
PPI port data register
.
Table 195. PPI Port Data Clear Register
16.3.6 PPI Port Data Set Register
The
PPI port data set register
is a 32-bit register containing 16 used bits, one for each of the general purpose
PPI
I/O pin. Each of the 16 bits corresponds to a bit in the
PPI port data register
.
The
PPI port data set register
is not a real hardware register, but is instead an address used to set bits in the
PPI
port data register
. When a write is performed to the
PPI port data set register
, each bit that is set to 1 results in
Address 0xE000 6014
Bit #
Name
Bit #
31:16
15:
0
31:16
RSVD
15:
0
PPUE[15:
0
]
Name
RSVD
PPUE[15:
0
]
Description
Reserved.
Port pull-up enable bits. If a bit in the register is 1, the corresponding
pin is connected to an internal pull-up.
Address 0xE000 601C
Bit #
Name
31:16
RSVD
15:
0
PDC[15:
0
]
Bit #
31:16
15:
0
Name
RSVD
PDC[15:
0
]
Description
Reserved.
Port data clear bits. When a write is performed to the
PPI port data
clear register
, each bit that is set to 1 results in the corresponding bit
in the
PPI port data register
being cleared to 0. The other bits of the
PPI port data register
remain unchanged.